Surface combustion burner

ABSTRACT

A surface combustion burner for burning a mixture of air and gaseous fuel. The burner includes a housing having an inlet for the air and gaseous fuel and an outlet covered by a layer of deformable, porous ceramic fibre material through which the air and gaseous fuel permeates and is lit on the surface. A foamed metal layer acts as a flame trap to prevent lighting back. An annular burner can be used to anneal a welded pipe.

United States Patent Badrock 1 Sept. 3, 1974 SURFACE COMBUSTION BURNER 3,216,478 11/1965 Saunders et al. 431 329 3,248,099 4/1966 B tk 431 329 [75] Inventor: Badmck southport Ergland 3,270,798 9/1966 431/329 73 Assignee; cooperheat, southport, England 3,751,213 8/1973 Sowards 431/328 [22] Filed: Mar. 30, 1973 4 [21] Appl. No.: 346,457 Primary ExaminerJ0hn J. Camby A F B W t B Related US. Application Data Attorney, gent, 0r zrm aldwln 1gh & rown [63] Continuation-impart of Ser. No. 260,433, June 7,

1972, abandoned.

[30] Foreign Application Priority Data [57] ABSTRACT June 6, 1972 Great Britain 19458/72 June 8, 1971 Great Britain 19458 71 A Surface Combustion bufherfor burning a mixture of air and gaseous fuel. The burner includes a housing 52 us. 01 431/328, 431/329, 432/225 having an inlet for the air and gaseous fuel and an 51 1111.01. F23d 13/12, F23d 13/14 let covered y a layer of deformable, porous Ceramic [58] Field of Search 431/328, 329; 432/224, fibre material through which the air and gaseous fuel 432 225 permeates and is lit on the surface, A foamed metal layer acts as a flame trap to prevent lighting back. An [56] Refer Ci d annular burner can be used to anneal a welded pipe.

UNITED STATES PATENTS 3,199,573 8/1965 Flynn 431/329 10 Claims, 2 Drawing Figures PATENIED E 31914 3,8@3.338

sum 10F 2 PAIENTEDSEP 3 1 3.8%.338

SHEEI 2 OF 2 SURFACE COMBUSTION BURNER This application is a continuation in part of application Ser. No. 260,433, filed on June 7, 1972, now abancloned.

FIELD OF INVENTION This invention relates to a surface combustion burner for burning a mixture of air and gaseous fuel. The burner can be used to anneal welded articles such as pipes.

DESCRIPTION OF PRIOR ART Surface combustion burners have been used for a long period of time but these known burners have previously employed either rigid refractory materials or stainless steel mesh for the burner face. Rigid refractory materials are liable to breakage and surface spalling and they occupy a large volume. It is also usual to require a special type of rigid refractory material which is porous enough to provide a low pressure drop across the burner face. Moreover rigid refractory materials cannot be configured, for example, to fit around a cylindrical pipe to form an annular burner and they would require to be specially made in curved shapes. Both rigid refractory materials and stainless steel are heavy and stainless steel is expensive.

SUMMARY OF INVENTION The present invention overcomes the problems noted above with regard to the prior art by providing a surface combustion burner comprising a housing having an inlet for air and gaseous fuel and an outlet which is covered by or in which is fitted, a layer or facing of deformable, porous, ceramic fibre material. The air and gas permeates the ceramic fibre layer and is lit on the surface. In order to reduce the risk of lighting back a thermally conductive layer, such as a layer of foamed metal, is used to back the ceramic fibre layer. The ceramic fibre layer is preferably a composite layer of ceramic fibre cloth and ceramic fibre blanket. The composite layer can be secured, by wire loops, to a perforate metal plate and can be held in position on flanges in the housing by a flanged cover which is bolted to the housing. The housing is preferably made of sheet metal both for lightness and ease of manufacture.

The invention therefore enables production of an inexpensive, light-weight surface combustion burner with an easily replaceable burner face which can be quickly erected to anneal welded articles, particularly those of an arcuate shape such as welded pipes. A particular advantage is that the burner face is easily deformable, for example by hand, so that it can be quickly configured to any one of a plurality of shapes, to fit a corresponding easily-erectable, light-weight sheet metal housing.

' Surface combustion burners can thereby be easily manufactured in a variety of shapes for heating different articles.

OBJECTS OF THE INVENTION An object of the invention is to provide an inexpensive, light-weight, surface combustion burner with an easily replaceable burner face and which can be quickly erected to anneal welded articles.

DESCRIPTION OF DRAWINGS The invention will become apparent from the embodiments which are described below with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an annular surface combustion burner in accordance with the invention, and

FIG. 2 is a sectioned elevation through another form of surface combustion burner in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, a housing 1 comprises a mild steel annulus of box-section of U-shaped in cross section. The open side of the annulus is covered with a layer of deformable, porous ceramic fibre material such as ceramic fibre cloth or ceramic fibre blanket 2. Housing 1 is in the form of an annulus to enable a pipe having a circumferential weld to be inserted therethrough so that the cloth or blanket 2 faces the weld. However, the housing can be of another shape, as explained below, to suit the shape, or area, of an article to be heated. Cloth or blanket 2 is secured to the internal edges of, or ledges 5 on, the annular mild steel box section by rivets or screws and washers 3. Housing 1 is provided with a tangential inlet in the form of a pipe 4 for a fully pre-mixed air/gas mixture.

In use, the air/ gas mixture permeates the pores of the cloth or blanket 2 and it is lit on surface. The whole face of the cloth or blanket 2 becomes incandescent and radiates heat to the workpiece, e.g. a circu'mferen- 1 tial weld in a pipe. The temperature of the surface of the cloth or blanket is dependent on the air to gas ratio. The combustion air is supplied from either a fan or a compressed air supply whilst clean fuel gas can be used.

The burners can be made in a variety of configurations e.g. straight burners, arced burners, and circular burners. The burners are useful for both preheat and postheat treatment of pipework, fabrications and vessels.

FIG. 2 illustrates a modified burner face which can be used with the embodiment described with reference to FIG. 1. The modified burner face is designed to reduce the risk of lighting back due to the interior surface of burner face reaching the ignition temperature of the air/gas mixture. In this embodiment the burner face comprises an upper layer arrangement of two layers of ceramic fibre cloth 6 and 7 backed by a lower layer comprising a ceramic fibre blanket 8, which cloth and blanket are both deformable and porous. The cloth layers 6 and 7 and the blanket 8 are held together by Inconel (registered trade mark) loops or stitches 9 anchored in a layer of expanded metal, or a wire mesh sheet 10. A final layer of foamed metal 16 serves as a flame trap to reduce the risk of lighting back.

The burner face is supported on flanges or ledges 11 extending from side walls .12 of the burner housing 13. An apertured or slotted trough-like cover 14 with inwardly facing flanges l5 fits over the housing 13 to secure the burner face. Ceramic paper gaskets can be inserted between the edges of the burner face and ledges 11 and flanges 15 to provide gastight joints. The trough 14 is bolted to the chamber 13. i

The thickness of the ceramic fibre cloth is typically 1/16 /8 inch (0.06 0.13 mm) but it can be thicker. The blanket can be made of Kerlane (Trade Mark) available in the U.I(. from Gloucester Saro Ltd. and reinforced with an Inconel (Trade Mark) netting.

The thickness of the burner face should be such as to reduce the risk of lighting back (preferably including a flame trap such as layer 16) but without being so thick that an undesirable pressure drop is caused across the burner face.

What is claimed is:

1. A surface combustion burner for burning a mixture of air and gaseous fuel, the surface combustion burner comprising a housing, said housing having an inlet and an outlet, said inlet being provided for said mixture of air and gaseous fuel and said outlet being covered with a composite layer of hand-deformable, permeable, ceramic fibre material, said composite layer including an upper layer of ceramic fibre cloth and a lower layer of ceramic fibre blanket, said upper layer being thin compared with said lower layer whereby said lower layer diffuses the mixture of air and gaseous fuel to the entire area of said upper layer to provide an ignitable mixture on an exterior surface of said upper layer.

2. A surface combustion burner according to claim 1 including a perforate metal sheet which supports said composite layer, said upper layer being secured to said lower layer by metal loops anchored in said perforate metal sheet.

3. A surface combustion burner according to claim 1 including a layer of hand-deformable thermally conductive material beneath said lower layer of ceramic fibre blanket, said layer of thermally conductive material serving as a flame-trap to reduce the risk of lighting-back.

4. A surface combustion burner according to claim 3 wherein said layer of thermally conductive material comprises a layer of foamed metal.

5. A surface combustion burner accordingrto claim 3 wherein the interior of said housing is provided with flanges on opposite walls and including an apertured cover provided with similar flanges, which cover is fitted to said housing, said flanges cooperating to secure therebetween the edges of said foamed metal layer, said perforate metal sheet and said composite layer.

6. A surface combustion burner' according to claim 5 wherein said housing is in the shape of an annulus.-

7. A surface combustion burner for burning a mixture of air and gaseous fuel, the surface combustion burner comprising a housing, said housing having an inlet and outlet, said inlet being provided for said mixture of air and gaseous fuel and said outlet being covered with a composite layer of hand-deformable, permeable,.ceramic fibre material and a layer of handdeformable thermally conductive material, said composite layer being positioned over said thermally conductive layer and said composite layer including an upper layer of ceramic fibre cloth and a lower layer of ceramic fibre blanket, said upper layer being thin compared with said lower layer whereby said lower layer diffuses the mixture of air and gaseous fuel to the entire area of said upper layer to provide an ignitable mixture on an exterior surface of said upper layer and sald thermally conductive layer serves as a flame-trap to reduce the risk of lighting-back.

8. A surface combustion burner according to claim 7 wherein said thermally conductive layer comprises foamed metal.

9. A surface combustion burner according to claim 8 wherein means for releasably securing said composite layer in said housing comprises an apertured annular cover having flanges cooperating with corresponding flanges on said housing.

10. A surface combustion burner according to claim 2 in which said metal loops engage said upper layer, extend through said lower layer and are anchored to said perforate metal sheet, thereby holding said upper and lower layers together to provide said composite layer. 

1. A surface combustion burner for burning a mixture of air and gaseous fuel, the surface combustion burner comprising a housing, said housing having an inlet and an outlet, said inlet being provided for said mixture of air and gaseous fuel and said outlet being covered with a composite layer of hand-deformable, permeable, ceramic fibre material, said composite layer including an uPper layer of ceramic fibre cloth and a lower layer of ceramic fibre blanket, said upper layer being thin compared with said lower layer whereby said lower layer diffuses the mixture of air and gaseous fuel to the entire area of said upper layer to provide an ignitable mixture on an exterior surface of said upper layer.
 2. A surface combustion burner according to claim 1 including a perforate metal sheet which supports said composite layer, said upper layer being secured to said lower layer by metal loops anchored in said perforate metal sheet.
 3. A surface combustion burner according to claim 1 including a layer of hand-deformable thermally conductive material beneath said lower layer of ceramic fibre blanket, said layer of thermally conductive material serving as a flame-trap to reduce the risk of lighting-back.
 4. A surface combustion burner according to claim 3 wherein said layer of thermally conductive material comprises a layer of foamed metal.
 5. A surface combustion burner according to claim 3 wherein the interior of said housing is provided with flanges on opposite walls and including an apertured cover provided with similar flanges, which cover is fitted to said housing, said flanges cooperating to secure therebetween the edges of said foamed metal layer, said perforate metal sheet and said composite layer.
 6. A surface combustion burner according to claim 5 wherein said housing is in the shape of an annulus.
 7. A surface combustion burner for burning a mixture of air and gaseous fuel, the surface combustion burner comprising a housing, said housing having an inlet and outlet, said inlet being provided for said mixture of air and gaseous fuel and said outlet being covered with a composite layer of hand-deformable, permeable, ceramic fibre material and a layer of hand-deformable thermally conductive material, said composite layer being positioned over said thermally conductive layer and said composite layer including an upper layer of ceramic fibre cloth and a lower layer of ceramic fibre blanket, said upper layer being thin compared with said lower layer whereby said lower layer diffuses the mixture of air and gaseous fuel to the entire area of said upper layer to provide an ignitable mixture on an exterior surface of said upper layer and saId thermally conductive layer serves as a flame-trap to reduce the risk of lighting-back.
 8. A surface combustion burner according to claim 7 wherein said thermally conductive layer comprises foamed metal.
 9. A surface combustion burner according to claim 8 wherein means for releasably securing said composite layer in said housing comprises an apertured annular cover having flanges cooperating with corresponding flanges on said housing.
 10. A surface combustion burner according to claim 2 in which said metal loops engage said upper layer, extend through said lower layer and are anchored to said perforate metal sheet, thereby holding said upper and lower layers together to provide said composite layer. 